The vast majority of pregnant women tested in a study published this year in the Journal of Nutrition were found to be deficient in vitamin D, as were their infants. Researchers from the University of Pittsburgh found widespread vitamin D deficiency, even though more than 90 percent of the women tested were taking vitamin supplements during pregnancy.

What you need to know
• Researchers evaluated blood tests on 200 black women and 200 white women who had been studied between 1997 and 2001. Blood samples taken from their infants at birth were also studied.
• More than 80 percent of black women and almost 50 percent of white women tested vitamin D deficient at pregnancy. The levels were even higher among infants; 92.4 percent of black babies and 66.1 percent of white babies were vitamin D deficient at birth.

• Vitamin D deficiency in infants can cause rickets, a softening of the bones that can lead to deformity and other complications. Low levels of vitamin D have also been linked to increased risk for asthma, Type 1 diabetes and schizophrenia. • Vitamin D concentrations among both black and white women were highest in the summer and lowest in the winter and spring. Among black women, however, summer levels were closer to the lower winter levels than among white women.

• The safest way to obtain vitamin D is by exposure to sunshine. For most people, 25 minutes of sun on the face and hands can cause the body to synthesize sufficient vitamin D. For lighter-skinned people, 10-15 minutes will suffice.
• Quote: "By the end of pregnancy, 90 percent of all women were taking prenatal vitamins and yet deficiency was still common." -- Marjorie L. McCullough, senior epidemiologist at the American Cancer Society